Field of the Invention
The present disclosure relates to generally to architecture for power consumption reduction in global navigation satellite system (GNSS) receivers, and more particularly, to GNSS receivers including a selectable low power signaling path and a selectable high power signaling path, which are configured to process signals received at the GNSS receiver based on a carrier-to-noise density (C/No) of the received signal.
Description of the Related Art
Multiple satellite navigation systems such as GPS (USA), Glonass (Russia), Beidou (China), and Galileo (Europe) are now emerging with each system transmitting from approximately 30 satellites, leading to greater than 120 navigation satellites that are available to consumer grade GNSS receivers (e.g. in smart phones). Each of these satellite navigation systems transmits on different frequencies with different signal structure, and there is a high probability that satellites from multiple satellite navigation systems will have a diverse range of received powers at the GNSS receiver. A challenge, therefore, for GNSS receiver developers is to provide simultaneous GNSS receiver access to all of the aforementioned satellite systems while reducing power consumption at the GNSS receiver.
Various factors may play a role in the received powers at the GNSS receiver. For example, received signal power at a user's antenna of the GNSS receiver may range from approximately 5 dB-Hz to 54 dB-Hz depending on antenna type and signal reception environment. For example, some antennas (e.g. patch antennas used for built-in car navigation systems) may have higher gain in the zenith direction, while some antennas (e.g. wire antennas in smart phones) may have a more isotropic antenna receive pattern. Received signal power of the received signals may also vary significantly due to signal blockage and fading, which may be caused by multipath phase altered version of the direct signal arriving at the GNSS receiver antenna.
Conventional GNSS receivers process the received signals using complex circuitry that is configured to mitigate interference associated with a received signal, e.g., when a received signals C/No is relatively low (e.g. less than or equal to 20 dB-Hz), to ensure that the information provided on the signal is processed successfully, e.g., to maintain minimum GNSS acquisition/tracking and measurement integrity; such complex circuitry uses a significant amount of power to process these signals.
Conventional GNSS receivers use the same complex circuitry to process received signals that have relatively high C/No (e.g. greater than or equal to 30 dB-Hz), which, in turn, may result in an unnecessary waste of power. More particularly, received signals with relatively high C/No, typically, have a significant design margin with respect to minimum GNSS acquisition/tracking and measurement thresholds and therefore may not require such complex circuitry. For example, if a particular GNSS satellite is received with a C/No of 50 dB-Hz there is approximately 20 dB-Hz of margin before measurement quality, and hence navigation accuracy, is overly effected. As can be appreciated, such received signals can, therefore, be processed using circuitry that is simpler than the complex circuitry used for processing a signal with relatively low C/No.
Therefore, there exists a need for GNSS receivers including a selectable low power signaling path and a selectable high power signaling path, which are configured to process signals received at the GNSS receiver based on a C/No of the received signal.